2 * Virtual cpu timer based timer functions.
4 * Copyright IBM Corp. 2004, 2012
5 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
8 #include <linux/kernel_stat.h>
9 #include <linux/export.h>
10 #include <linux/kernel.h>
11 #include <linux/timex.h>
12 #include <linux/types.h>
13 #include <linux/time.h>
15 #include <asm/cputime.h>
16 #include <asm/vtimer.h>
17 #include <asm/vtime.h>
18 #include <asm/cpu_mf.h>
23 static void virt_timer_expire(void);
25 static LIST_HEAD(virt_timer_list);
26 static DEFINE_SPINLOCK(virt_timer_lock);
27 static atomic64_t virt_timer_current;
28 static atomic64_t virt_timer_elapsed;
30 DEFINE_PER_CPU(u64, mt_cycles[8]);
31 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
32 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
33 static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
35 static inline u64 get_vtimer(void)
39 asm volatile("stpt %0" : "=m" (timer));
43 static inline void set_vtimer(u64 expires)
48 " stpt %0\n" /* Store current cpu timer value */
49 " spt %1" /* Set new value imm. afterwards */
50 : "=m" (timer) : "m" (expires));
51 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
52 S390_lowcore.last_update_timer = expires;
55 static inline int virt_timer_forward(u64 elapsed)
57 BUG_ON(!irqs_disabled());
59 if (list_empty(&virt_timer_list))
61 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
62 return elapsed >= atomic64_read(&virt_timer_current);
65 static void update_mt_scaling(void)
67 u64 cycles_new[8], *cycles_old;
68 u64 delta, fac, mult, div;
71 stcctm5(smp_cpu_mtid + 1, cycles_new);
72 cycles_old = this_cpu_ptr(mt_cycles);
75 for (i = 0; i <= smp_cpu_mtid; i++) {
76 delta = cycles_new[i] - cycles_old[i];
84 /* Update scaling factor */
85 __this_cpu_write(mt_scaling_mult, mult);
86 __this_cpu_write(mt_scaling_div, div);
87 memcpy(cycles_old, cycles_new,
88 sizeof(u64) * (smp_cpu_mtid + 1));
90 __this_cpu_write(mt_scaling_jiffies, jiffies_64);
94 * Update process times based on virtual cpu times stored by entry.S
95 * to the lowcore fields user_timer, system_timer & steal_clock.
97 static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
99 struct thread_info *ti = task_thread_info(tsk);
100 u64 timer, clock, user, system, steal;
101 u64 user_scaled, system_scaled;
103 timer = S390_lowcore.last_update_timer;
104 clock = S390_lowcore.last_update_clock;
106 " stpt %0\n" /* Store current cpu timer value */
107 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
108 " stckf %1" /* Store current tod clock value */
110 " stck %1" /* Store current tod clock value */
112 : "=m" (S390_lowcore.last_update_timer),
113 "=m" (S390_lowcore.last_update_clock));
114 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
115 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
117 /* Update MT utilization calculation */
119 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
122 user = S390_lowcore.user_timer - ti->user_timer;
123 S390_lowcore.steal_timer -= user;
124 ti->user_timer = S390_lowcore.user_timer;
126 system = S390_lowcore.system_timer - ti->system_timer;
127 S390_lowcore.steal_timer -= system;
128 ti->system_timer = S390_lowcore.system_timer;
131 system_scaled = system;
132 /* Do MT utilization scaling */
134 u64 mult = __this_cpu_read(mt_scaling_mult);
135 u64 div = __this_cpu_read(mt_scaling_div);
137 user_scaled = (user_scaled * mult) / div;
138 system_scaled = (system_scaled * mult) / div;
140 account_user_time(tsk, user);
141 tsk->utimescaled += user_scaled;
142 account_system_time(tsk, hardirq_offset, system);
143 tsk->stimescaled += system_scaled;
145 steal = S390_lowcore.steal_timer;
146 if ((s64) steal > 0) {
147 S390_lowcore.steal_timer = 0;
148 account_steal_time(steal);
151 return virt_timer_forward(user + system);
154 void vtime_task_switch(struct task_struct *prev)
156 struct thread_info *ti;
158 do_account_vtime(prev, 0);
159 ti = task_thread_info(prev);
160 ti->user_timer = S390_lowcore.user_timer;
161 ti->system_timer = S390_lowcore.system_timer;
162 ti = task_thread_info(current);
163 S390_lowcore.user_timer = ti->user_timer;
164 S390_lowcore.system_timer = ti->system_timer;
168 * In s390, accounting pending user time also implies
169 * accounting system time in order to correctly compute
170 * the stolen time accounting.
172 void vtime_account_user(struct task_struct *tsk)
174 if (do_account_vtime(tsk, HARDIRQ_OFFSET))
179 * Update process times based on virtual cpu times stored by entry.S
180 * to the lowcore fields user_timer, system_timer & steal_clock.
182 void vtime_account_irq_enter(struct task_struct *tsk)
184 struct thread_info *ti = task_thread_info(tsk);
185 u64 timer, system, system_scaled;
187 timer = S390_lowcore.last_update_timer;
188 S390_lowcore.last_update_timer = get_vtimer();
189 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
191 /* Update MT utilization calculation */
193 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
196 system = S390_lowcore.system_timer - ti->system_timer;
197 S390_lowcore.steal_timer -= system;
198 ti->system_timer = S390_lowcore.system_timer;
199 system_scaled = system;
200 /* Do MT utilization scaling */
202 u64 mult = __this_cpu_read(mt_scaling_mult);
203 u64 div = __this_cpu_read(mt_scaling_div);
205 system_scaled = (system_scaled * mult) / div;
207 account_system_time(tsk, 0, system);
208 tsk->stimescaled += system_scaled;
210 virt_timer_forward(system);
212 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
214 void vtime_account_system(struct task_struct *tsk)
215 __attribute__((alias("vtime_account_irq_enter")));
216 EXPORT_SYMBOL_GPL(vtime_account_system);
219 * Sorted add to a list. List is linear searched until first bigger
222 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
224 struct vtimer_list *tmp;
226 list_for_each_entry(tmp, head, entry) {
227 if (tmp->expires > timer->expires) {
228 list_add_tail(&timer->entry, &tmp->entry);
232 list_add_tail(&timer->entry, head);
236 * Handler for expired virtual CPU timer.
238 static void virt_timer_expire(void)
240 struct vtimer_list *timer, *tmp;
241 unsigned long elapsed;
244 /* walk timer list, fire all expired timers */
245 spin_lock(&virt_timer_lock);
246 elapsed = atomic64_read(&virt_timer_elapsed);
247 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
248 if (timer->expires < elapsed)
249 /* move expired timer to the callback queue */
250 list_move_tail(&timer->entry, &cb_list);
252 timer->expires -= elapsed;
254 if (!list_empty(&virt_timer_list)) {
255 timer = list_first_entry(&virt_timer_list,
256 struct vtimer_list, entry);
257 atomic64_set(&virt_timer_current, timer->expires);
259 atomic64_sub(elapsed, &virt_timer_elapsed);
260 spin_unlock(&virt_timer_lock);
262 /* Do callbacks and recharge periodic timers */
263 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
264 list_del_init(&timer->entry);
265 timer->function(timer->data);
266 if (timer->interval) {
267 /* Recharge interval timer */
268 timer->expires = timer->interval +
269 atomic64_read(&virt_timer_elapsed);
270 spin_lock(&virt_timer_lock);
271 list_add_sorted(timer, &virt_timer_list);
272 spin_unlock(&virt_timer_lock);
277 void init_virt_timer(struct vtimer_list *timer)
279 timer->function = NULL;
280 INIT_LIST_HEAD(&timer->entry);
282 EXPORT_SYMBOL(init_virt_timer);
284 static inline int vtimer_pending(struct vtimer_list *timer)
286 return !list_empty(&timer->entry);
289 static void internal_add_vtimer(struct vtimer_list *timer)
291 if (list_empty(&virt_timer_list)) {
292 /* First timer, just program it. */
293 atomic64_set(&virt_timer_current, timer->expires);
294 atomic64_set(&virt_timer_elapsed, 0);
295 list_add(&timer->entry, &virt_timer_list);
297 /* Update timer against current base. */
298 timer->expires += atomic64_read(&virt_timer_elapsed);
299 if (likely((s64) timer->expires <
300 (s64) atomic64_read(&virt_timer_current)))
301 /* The new timer expires before the current timer. */
302 atomic64_set(&virt_timer_current, timer->expires);
303 /* Insert new timer into the list. */
304 list_add_sorted(timer, &virt_timer_list);
308 static void __add_vtimer(struct vtimer_list *timer, int periodic)
312 timer->interval = periodic ? timer->expires : 0;
313 spin_lock_irqsave(&virt_timer_lock, flags);
314 internal_add_vtimer(timer);
315 spin_unlock_irqrestore(&virt_timer_lock, flags);
319 * add_virt_timer - add an oneshot virtual CPU timer
321 void add_virt_timer(struct vtimer_list *timer)
323 __add_vtimer(timer, 0);
325 EXPORT_SYMBOL(add_virt_timer);
328 * add_virt_timer_int - add an interval virtual CPU timer
330 void add_virt_timer_periodic(struct vtimer_list *timer)
332 __add_vtimer(timer, 1);
334 EXPORT_SYMBOL(add_virt_timer_periodic);
336 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
341 BUG_ON(!timer->function);
343 if (timer->expires == expires && vtimer_pending(timer))
345 spin_lock_irqsave(&virt_timer_lock, flags);
346 rc = vtimer_pending(timer);
348 list_del_init(&timer->entry);
349 timer->interval = periodic ? expires : 0;
350 timer->expires = expires;
351 internal_add_vtimer(timer);
352 spin_unlock_irqrestore(&virt_timer_lock, flags);
357 * returns whether it has modified a pending timer (1) or not (0)
359 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
361 return __mod_vtimer(timer, expires, 0);
363 EXPORT_SYMBOL(mod_virt_timer);
366 * returns whether it has modified a pending timer (1) or not (0)
368 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
370 return __mod_vtimer(timer, expires, 1);
372 EXPORT_SYMBOL(mod_virt_timer_periodic);
375 * Delete a virtual timer.
377 * returns whether the deleted timer was pending (1) or not (0)
379 int del_virt_timer(struct vtimer_list *timer)
383 if (!vtimer_pending(timer))
385 spin_lock_irqsave(&virt_timer_lock, flags);
386 list_del_init(&timer->entry);
387 spin_unlock_irqrestore(&virt_timer_lock, flags);
390 EXPORT_SYMBOL(del_virt_timer);
393 * Start the virtual CPU timer on the current CPU.
395 void vtime_init(void)
397 /* set initial cpu timer */
398 set_vtimer(VTIMER_MAX_SLICE);
399 /* Setup initial MT scaling values */
401 __this_cpu_write(mt_scaling_jiffies, jiffies);
402 __this_cpu_write(mt_scaling_mult, 1);
403 __this_cpu_write(mt_scaling_div, 1);
404 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));